Piston ring



Patented J ne'so, 1942 UNITED. STATES PATENT OFFICE PISTON RING Walter E. J ominy, Detroit, Mich, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 2, 194b, Serial No. 343,588

Claims. (01. 309-44) This invention relates to piston rings; and

' especially to piston rings for maintaining the requisite seal between the piston and cylinder of an internal combustion engine.

The object-of the invention is a piston ring having improved resistance to scufflng and wear.

' The above and other objects of the invention will be apparent as the description proceeds. According to the. invention, the piston ring, which may be of cast iron or steel, has, in its rubbing surface, ,fine circumferential grooves which are lined or partially filled with tin or any other suitable relatively soft metal. The partial filling of-the grooves with tin orthe like may be effected by electro-plating the rubbing surface of the piston ring with the soft metal; to

a thickness suiiicient -toline without filling the grooves, and then removing substantially all the.

plating from over the rubbing surface ring, to size. v 1

The drawing shows one construction according to the invention.

In the drawing:

7 of the Fig. 1 is a sectional view of an engine cylinder showing therein a piston to which three packing rings (one shown in section), according to the invention, have been applied.

Fig. 2 is an enlarged sectional view of one of I the piston rings, showing untinned. v

Fig. 3 is an enlarged sectional view of the same piston ring after its rubbing surface has been tin plated, and the grooves have ,been partially filled with tin.

the grooves therein,

Fig. 4 is an enlarged sectional view of the same piston ring after it has been machined to size by the removal of the plating from the rubbing surface of the ring.

In Fig.1, the. piston rings I, 2' and a, are

In the example illustrated, the piston ring is .125" wide, and the four grooves therein are .010" wide and .015" deep. The grooves are separated by .015", while the topmost and lowermost grooves are '.02'0" from the edges of the .While the grooves in the piston ring might be lined with tin in other ways, as by spraying molten tin therein, or hammering -a strip of tin therein, it has been found that the plating process is amost convenient way of doing this.

'It will be observed from an examination of -Fig. 4, that the tin plating in the grooves extends out to-the rubbing surface of the piston ring which thereby is comprised of a seriesiof annular laminated areas of a hard metal, a softmetal, a space, a soft metal, and a hard metal,

in succession, or expressed otherwise, that there 2 are spaced circumferential bands of soft metal in the cylindrical surface of the ring, with cir-Q cumferential oil grooves in the soft "metal.

' The piston ring has improved life, probably ,for the reason that it has a plurality of edges of anti-friction material formed by the tin and the oil grooves. therein, and that throughout the life of the ring a small quantity of the tin, well lubricated by the oil in thegrooves therein, is wiped over the rubb surface of the ring, which has an adequate area of the harder springy metal to maintain a long lived seal between the piston and the cylinder. However, this may be, it has been found that the ring has greatly improved resistance to scufling and wear, and a very much longer life than any, other type of pistomring, under the very onerous conditions ina Diesel engine.

- In some circumstances a thin layer of tin might,be left over the surface of the rings.

I claim:

1. A piston ring having a circumferential rub bing surface, an oil groove in said surface, said 011 groove being lined with-an antlfriction material extending to said rubbing surface.

2, A piston ring having a plurality of circum-' ferential oil grooves in its rubbing surface, said oil grooves "being lined with tin extending to the rubbing surface of the piston ring.

3, A piston ring having a circumferential rubbing surface, comprised of annular laminated areas of a hard metal, and a soft metal, .and having an annular oil-groove in one of said areas.

4. A. piston ring of hard metal having a-plu- 1 rality of circumferential oil grooves in its rubbing surface, said oil grooves beingllned with a soft anti-friction metal extending out to the rubhing. surface of the piston ring, whereby the rubbingsurface of the piston rings is comprised of a series of annular laminated areas of a hard metal, a soft metal, a space; a soft metal and a hard metal, in succession.

ring. The oftin plating It, as shown '1 in Figs. 3 and 4 is about .004". It wilfbe noted that the cross-sectional dimensions of the lined grooves are acmally very small.

5. The combination according to claim 4, n,

which the ring is about .125" 'widefand there are four grooves therein, each about .010" wide and .015" deep, separated by-about .015".

WALTER 1:. mm. 

